Circadian Influence on Prolonged Exposure Therapy for PTSD

Inclusion Criteria:

1. a diagnosis of PTSD as defined by DSM-5, with a minimum CAPS severity score of 26, aminimum PCL-5 score of 31, or a score of 2 or above on CAPS-5 Item B2 (concerningdistressing dreams)

2. interest in starting a course of PE

3. availability for appointments at that will either begin from 07:00 to a time nolonger than 2 hours past their customary rise time, or to the last treatment sessionof the day beginning at 16:00 or later

4. Age range of 18-70

5. A Morningness-Eveningness Questionnaire (MEQ) score above 25.

6. Non-exclusionary psychotropic medications must have been stable for 3 weeks prior toScreening/Assessment with intention to remain stable throughout participation.

Exclusion Criteria:

1. current or past history of bipolar I disorder, schizophrenic or other psychoticdisorders,

2. current organic brain disorder including moderate to severe traumatic brain injury

3. factitious disorder or malingering

4. pregnant or planning to become pregnant in the next four months at time of screening [if a participant does become pregnant during study procedures, the situation willbe reviewed on a case-by-case basis and the participant's wishes will be consideredin deciding whether the participant will continue with the study or withdraw.]

5. current moderate or severe substance use disorder with symptoms present within thepast three months

6. diagnosed moderate to severe sleep apnea, narcolepsy, periodic limb movement, orrestless legs syndrome that result in daytime sleepiness indicated by EpworthSleepiness Scale (ESS) above 10

7. active risk of harm to self or others

8. evidence of clinically significant hepatic or renal disease or any other acute orunstable medical condition that might interfere with safe conduct of the study

9. current participation in trauma-focused cognitive-behavioral therapy (e.g.,Cognitive Processing Therapy, Written Exposure Therapy, Eye Movement Desensitizationand Reprocessing Therapy)

10. prior treatment with an adequate dose of PE (i.e., 8 or more sessions) to thetraumatic event that would be the index trauma for treatment in the study

11. having no memory of their traumatic event

12. daily use of benzodiazepines

13. methadone or suboxone maintenance therapy for past opioid addiction

14. diagnosis of Cushing's disease, Addison's disease or use of medications that targetcortisol directly such as those used to treat Cushing's disease [ketoconazole,mitotane (Lysodren), metyrapone (Metopirone), and Mifepristone (Korlym, Mifeprex)],those used to treat Addison's disease [Hydrocortisone (Cortef), prednisone ormethylprednisolone], as well as cortisone or dexamethasone.

15. persons who would habitually awaken so early that more than 2 h would elapse beforea morning PE session could occur; or those who engage in habitual shiftwork ortransmeridian travel